CsPbCl₃-Driven Low-Trap-Density Perovskite Grain Growth for >20% Solar Cell Efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Charge recombination at grain boundaries is a major limitation in perovskite (PVK) solar cell performance.
• Effective passivation of these trap states is crucial for improving device efficiency and stability.

Purpose of the Study:

• To develop a novel strategy for passivating trap states at grain boundaries in PVK solar cells.
• To investigate the mechanism of passivation and its impact on device performance.

Main Methods:

• Introduction of a CsPbCl3 coating prior to PVK deposition.
• Analysis of ion migration and reaction at grain boundaries at elevated temperatures.
• Characterization of PVK films using photoluminescence intensity, carrier lifetime, and trap state density measurements.

Main Results:

• A passivating PbI2 layer is formed at grain boundaries via CsPbCl3 coating and Cl- ion migration.
• Passivation leads to increased photoluminescence intensity, extended carrier lifetime, and reduced trap state density.
• Optimized PVK solar cells achieve 20.09% efficiency with reduced hysteresis and enhanced stability.

Conclusions:

• The CsPbCl3 coating strategy effectively passivates grain boundary trap states in PVK solar cells.
• This passivation method significantly improves device efficiency and stability without altering film morphology.
• The findings offer a promising route for advancing high-performance perovskite solar cell technology.